Observational data reveal evidence and parameters of contagious yawning in the behavioral repertoire of captive-reared chimpanzees (Pan troglodytes)

Abstract

There is robust experimental evidence for contagious yawning, yet observational studies of naturalistic behavior have been fewer. Without data from real-world behavior, researchers have questioned the existence of contagious yawning and made assumptions about some parameters (e.g., the duration of the effect). We observed contagious yawning in chimpanzees to confirm/disconfirm its existence in the behavioral repertoire of this species, and if present, provide some of the missing descriptives. We recorded yawns on an all-occurrence basis from 18 captive-reared chimpanzees at the Los Angeles Zoo. We recorded identity, time, and individuals who could have been affected. We calculated a threshold for contagion by taking the mean and adding 1.96 standard deviations, constructing a response curve. Across multiple measures we see a consistent pattern in which there is a strong effect of contagion for 1.5 minutes, a less strong but still significant effect lasting up to 3.5 minutes in some measures, and no evidence of contagion beyond 3.5 minutes. From the time stamp on each yawn we were able to rule out temporal synchrony as an alternative hypothesis. Thus, contagious yawning appears to be a natural phenomenon in chimpanzees lending support to the myriad experimental and observational studies to date.

The neuroethology of spontaneous mimicry and emotional contagion in human and non-human animals

“…Delayed Facial Mimicry (DFM) usually occurs with a delay of one to five seconds after presentation of the stimulus (Davila-Ross et al, 2011;Palagi et al, 2018a). Yawn contagion occurs when someone yawns in response to another's yawn: this response delay can range from less than 1 s (falling in the range of RFM), 1 to 5 s (falling in the range of DFM) or, more frequently, extends to several minutes, with a peak response within the first 3/3.5 minutes (Palagi et al, 2009;Palagi et al, 2014;Campbell and Cox, 2019). It is therefore under debate whether and to what extent yawn contagion is the expression of other forms of mimicry (Yoon and Tennie, 2010).…”

“…Yawn contagion has been found in all the hominine species: chimpanzees (Pan troglodytes: Anderson et al, 2004;Campbell and de Waal, 2011;Campbell and Cox, 2019), bonobos (Pan paniscus; Demuru and Palagi, 2012;; but see: Amici et al, 2014 on a vary small sample size) and humans (Homo sapiens: Provine, 1986;1989). Outside the hominine species but still within the hominid family, two reports failed to find yawn contagion in lowland gorillas J o u r n a l P r e -p r o o f (Gorilla gorilla; Amici et al, 2014; on a larger sample including a bachelor and a harem group: Palagi et al, 2019).…”

Yawn contagion in domestic pigs (Sus scrofa)

“…In particular, the presence of yawn contagion has been found only in highly social species and seems to be linked to the type of sociality more than to the phylogenetic closeness 9 . For example, in primates yawn contagion seems not to be expressed in species with relatively low levels of affiliation or tolerance (strepsirrhines: ring-tailed lemurs, Lemur catta, and ruffed lemurs, Varecia variegata 10,11 ; the cercopithecid, Japanese macaque 12 ; the hominid, lowland gorilla; Gorilla gorilla 13,14 ) whereas it is present in other (in some cases phylogenetically close) species showing higher levels of social affiliation (cercopithecids: Tonkean macaque 12 ; geladas 4 ; hominids: chimpanzees [15][16][17] ; bonobo, Pan paniscus 13,18,19 ; humans 1,6 ). Yawn contagion has been also found in non-primate species characterized by high inter-individual cohesion, including mammals (wolves, Canis lupus lupus 20 ; sheep, Ovis aries 21 ; some groups of elephant seals, Mirounga leonina 22 ), and one social bird species (budgerigar, Melopsittacus undulates 23 ).It has been hypothesized that the emergence of yawn contagion has been favored by natural selection in highly social species to enhance synchronization between individuals (spatial ranging, coordinated foraging, and sleep/wake rhythms 9 ).…”

Intraspecific Motor and Emotional Alignment in Dogs and Wolves: The Basic Building Blocks of Dog–Human Affective Connectedness

“…Contagious yawning, a behavioral act involuntarily induced by viewing or listening other's yawns [64], is considered as a different phenomenon which has been widely demonstrated in human and non-human primates [67][68][69][70][71]. In primates, yawn contagion can be considered as a proxy of emotional contagion and it can be associated with the level of social attachment between partners [5].…”

“…In primates, yawn contagion can be considered as a proxy of emotional contagion and it can be associated with the level of social attachment between partners [5]. Even though in human and non-human primates the social modulation of contagious yawning is supported by ethological [68][69][70][71], neurological [72,73], and psychological evidence [74], contradictory results about proximate mechanisms of contagion emerged from the studies on domestic dogs.…”